The present invention relates to a novel acrylicized polyetherpolyol which can be used in particular for radiation-curable coating compositions.
It is known to cure compositions based on acrylic esters by means of radiation, especially UV radiation. Here, however, a problem which arises is that the presence of air in the course of curing, especially the curing of surfaces, is disruptive.
DE-C 2625538 discloses photopolymerizable coating compositions comprising amines as reducing agents and chain-transfer compounds. The use of a free amine of this kind has the disadvantage that it may act as a plasticizer, and leads to an unwanted deposit on the surface.
By incorporating the amino group into a molecule which also includes polymerizable groups, a copolymerized amine is obtained which does not have the abovementioned disadvantages. A known method of incorporation is the adding of amines onto double bond-rich molecules, which proceeds in the manner of a Michael addition and is described, for example, in F. Moller, Houben-Weyl, Vol. 11/1 (1957), pp. 277-280. U.S. Pat. No. 2,759,913 teaches the addition of amines onto activated, olefinically unsaturated compounds, such as acrylates in equimolar amounts, which leads to the complete reaction of the activated ethylenic double bonds. Systematic investigations into the addition of amino alcohols onto acrylates have been carried out by Ogata. Bull. Chem. Soc. Jap. 39, pages 1486-1490, 1966.
DE-C 2 346 424 describes the preparation of radiation-curable compositions starting from acrylic esters of polyhydric alcohols and from secondary, aliphatic monofunctional amines. These compositions have the disadvantage of reduced stability on storage. The adding-on of a secondary amine, moreover, leads to a reduction in the acrylic ester functionality of the molecule and hence also to a reduction in the crosslinking possibilities for radiation-induced polymerization.
EP Application 0280222 discloses adducts of acrylic esters and a polyhydric alcohol with a primary monoamine, which are used for radiation-curable coating compositions.
EP-B 0586849, furthermore, discloses amino acrylates having a viscosity of from 2000 to 3000 mPas, a content of olefin double bonds of from 8 to 20% by weight and a nitrogen content of from 0.4 to 2.0% by weight, which can be employed as binders for radiation-curable coating compositions.
The disadvantage of the said products lies in the tendency towards yellowing, especially of the amine-modified polyether acrylates.